Adjustable curved ruler



Jan. 10, 1933. w 5 WESTON 1,893,690

ADJUSTABLE CURVED RULER Filed July 28; 1950 3 Sheets-Sheet l IN ws/v TOR Jan. 10, .1933. w. s. WESTON ADJUSTABLE CURVED RULER Filed July 28, 1930 5 Sheets-Sheet 3 v 'v v MA [mew TOR.-

W/'///'am 5. W66 70/? @M/ K $4M (77 Patented Jan. 10, 1933;

UNITED STATES WILLIAM S. WESTON, F DALLAS, TEXAS ADJIJ'STABLE GURVED RULE-R Application filed July 28,

My present invention relates to novel modifications and improvements in the form and construction of the curve scriber covered by United States Patent No. 1,061,345, granted to me May 13, 1913. It relates particularly to a modification in which the main parts constituting the longitudinally extending flexible portion carrying the ruling edge, together with the lever arms attached to the flexible portion at fixed angles thereto, are all integrally made and formed from one piece of material of hard and highly resilient quality, like sheet steel.

The invention in detail consists in the features of novelty hereinafter set forth, illustrated in the accompanying drawings and more particularly pointed out in the appended claims.

In the drawings Fig. 1 is a plan or top view of the curve ruler set to the straight line position. Fig. 2 is a view in elevation of the left hand end of Fig. 1. Fig. 3 is a plan view with the flexible body curved for ruling a circular are through approximately 90 degrees. Fig.4 illustrates the blank as first punched from sheet steel or other elastic material, and which is afterward to be folded to the form of Fig. 1. Fig. 5 is an end view from the left of Fig. 1, drawn in enlarged scale. Fig. 6 is a cross section on the line 66 of Fig. 1, as seen from the left, also in enlarged scale, and illustrates the relation of the parts of the flexible body and its controlling arms. Fig. 7 is a separate view in elevation on the same scale as Figs. 5 and 6 illustrating the clamp screw and plate used on each end extension for holding the instrument to any adjusted curvature. Fig. 8 il lustrates one-half of an instrument made with only the outside portion of Fig. 1, made substantially from a blank similar to the upper two-thirds ofthe blankillustrated in Fig. 4. Fig. 9 illustrates an instrument similar to that of Fig. 8'except that it is provided with an auxiliary flexible member. Figs. 10 and 11 are diagrams illustrating how the relative spread between the points where each pair of arms is attached to the flexible body, and which uniformly increases or decreases 1930. Serial No. 471,124.

from one end to the other of that body, may be determined mathematically.

Referring to the drawings, the improved curve ruler in its preferred form comprises a longitudinally extending flexible body formed of three strips or ribbons of steel, or like resilient material, set with their curving surfaces in close contact. In the following description the ribbon A on the convex side of Fig. 3 is called the outside ribbon. ,B is the middle ribbon and C the inside ribbon. The bottom edge of ribbon A is integrally connected to the top edge of ribbon B through the medium of pairs of arms den and db, see Figs. 6 and 8. The arms of each pair comprise the sides of a V as seen in plan View, with the ends at the apex of the V integrally connected by a short bend d of the same diagonal strip in the blank from which the arms are formed. This short connection (Z is flexible in a tortional way, permitting a relative small closing or opening of the angle of the V and takes the place of the mechanical pivot in my prior device. Since the arms do and (lb do not lay in the same plane, but are spaced one above the other an amount equal to the bend d. the opening or closing of the angle of the V will-also be accompanied by a tortional bending strain in the arms. On the other hand, the connections of the arms do and (lb at the upper ends of the V with the bodyribbons A and B respectively are direct to the edge of these ribbons, when the blank is correctly folded to the dotted lines of'Fig. 4, so that the angle of 'con- 5 nection cannot materially change.

- The fundamental principle of operation of the device, whereby the curvature of the flexible body may be Varied, is embodied in the combination of at least two ribbons through the medium of the series of V-shaped arms,

as thus far described, and can now be stated.

-When the instrument is changed from the straight line shape of Figure 1 to a curved shape like that of Figure 3 by manually bringing the ends toward each other, the ribbon A is moved to the right on ribbon B. Fhismov'ement is produced and the curvature assumed by the ribbons A and B is governedor controlled through the medium of the V pairs of arms. As previously stated, the angle of the connection of the arms (E64 and db with the ribbons is practically unyielding, while the angle between the arms, i. e., the angle of the V, is yielding. The manual act of bringing the instrument to the position of Figure 3 therefore causes an increase in the angle of the Vs, resulting in the sliding movement of the ribbon A on the ribbon B with an automatic distribution of the curvature, the curvature subtending, each V being equal to the increase in the angle. The amount that ribbon A is slidably moved on ribbon B will determine the curvature; an increase in the movement accomplishing a. shortening of the radius of curvature.

Referring to Figs. 1 to 6, the preferred form of my present invention, the bottom edge of ribbon B is connected to the top edge of inside ribbon C through the medium of pairs of arms 66 and 60, substantially the same construction as in the connection between ribbons A and B. In the forming of the device the V form of arms 66 and 60 is folded within that of arms (Z0 and (lb and is relatively slightly smaller, as indicated in Figs. 1 and 6. Referring particularly to Fig. 6, it will be noted the bend 6 connecting the arms 6?) and 60 at the apex of the V is slightly shorter than apparently necessary. The bend is made shorter to avoid any material friction in the contact between the two sets of Vs at the time the device is being adjusted from the straight line shape of Fig. 1 to that of any desired curvature like that of Fig. 3.

A novel detail in the construction of my improved device may now be described. The ribbons of the longitudinal flexible body whose curvature is controlled by the V form pairs of arms connecting adjacent ribbons, are located concentrically to each other so that the radius of curvature of any ribbon differs from the radius of the adjacent ribbon an amount equal to the thickness of the ribbon. For example, the radius of ribbon B in Fig. 3 is less than that of ribbon A and greater than that of ribbon C an amount equal to the thickness of the ribbon, all three ribbons being of the same thickness. Considering ribbons A and B only, it will be obvious now that in changing from the straight line relation of Fig. 1 to the curved relation of Fig. 8, accomplished by the relative movement of ribbon A toward the right, that the amount of that relative movement on the arc of a circle gradually decreases toward the ually reduced toward the right in order that the curvature controlled by the increase of the spread, as already described, shall be uniformly that of the arc of a circle for the full length of the flexible body.

The above detail can be more clearly defined by means of the diagrams Figs. 10 and 11. Lines A1 and B1 are the center lines of two flexible ribbons in close contact. The distance between the center lines is indicated by the letter 1". Only two V form pairs of arms are indicated, one near each end of the flexible ribbons located at a distance K from each other, measured center to center in the straight line position. The connections between the arms and the ribbons are rigid at constant angles, while the connection between the arms at the apex of the V is flexible, as previously described. The connections between the arms and the ribbons are so related that the ribbon A1 when it is moved to the right as indicated in Fig. 11, becomes the outside ribbon of a convex curve, the radius of which is governed by an increase in the spread of the Vs. It will be obvious at a glance that for an arc of constant radius, with ribbon Al on the outside of ribbon B1 the amount of the increase in the spread will gradually decrease toward the right.

The mathematical problem in the manufacture of the device is to determine the relative value of the spreads of the Vs in the straight line position, like spreads m and w of Fig. 10, such that their increase it and 7' respectively, accompanied by the curvature of the ribbons as shown in Fig. 11, will pro vide for an arc of the same radius. In the manufacture of the instrument, the straight line spread 97?. and depth n of the left hand V may be chosen arbitrarily. The depth of all the We is preferably made the same. For any chosen radius of curvature R for ribbon B in combination with the depth a of the Vs and the straight line spread m, the increase h in the spread of the left hand V may be determined. From the values R and h in combination with r, the center distance between the two ribbons, and the angle covered by the straight line distance K between the two Vs, the increase 9' of the spread of the right hand V may also be determined. From the diagram of Fig. 11 it may now be shown that the ratio of spread m to spread m is equal, within practical finite limits, to the ratio of their increases j and h. Expressed by an equation m h or x 7 h e For the consecutive V pairs of arms to be located between those shown in Fig. 10, the spread is gradually reduced from m to 00. To the right of w the reduction of spread would continue at the same rate, while to the left of m it would be an increase of spread at the same rate.

The same method as above is to be used in determining the spreads of the inside V pairs of arms connecting ribbons B and C of Fig. 1, taking into account that the depth of those V5 is slightly less than for those connecting ribbons A and B. i

It isnow to be noted in Fig. 3 that both ribbons A and C have been moved to the right relative to ribbon B. Considerin ribbons B and C alone, B on the outside of a, ribbon B may be said to have moved to the left relative to ribbon C with the result that the spread of the inside Vs gradually reduce toward the left. Another important detail incidental to this construction is that arms d?) of the outside Vs and arms 0?) of the inside Vs are all attached to ribbon B inclined toward the same end, as more clearly shown in Fig. 1-, the points of attachment being in. staggered relation. By this construction the curving of ribbon B is to a certain extent the result of a consecutive series of extremely small bends between the points of attachment of the arms. The resulting curve is sufliciently smooth for all practical uses while this construction is in a measure a safeguard against distortion through abnormal strains.

Referring to Fig. 4, illustrating the blank as punched from flat material, the parts which constitute the flexible ribbons, the V pairs of arms, and the tangent end extensions are now clearly distinguishable. The straight through lines along which the blank is to be folded when brought into the final shape of Fig. 1 are indicated by dotted lines. The end extensions are in three parts attached to the ends of the three flexible ribbons and in the final form of Fig. 1 are free to move with the ribbons in their relative longitudinal movement. The extensions at each end are folded about a rectangular plate 6 as indicated in Fig-5. The extensions A and A attached to ribbon A are made large enough to enfold the other two parts, the faces formed by the fold being indicated by the numbers 1 to 5. The faces after the fold of the extensions attached to ribbon B are indicated by the numbers 6, 7 and 8. The faces of the extensions attached to ribbon C are indicated by numbers 9 and 10. To hold the end extensions against further relative movement after the instrument has been adjusted to any desired curvature, a clamp screw 8, as shown in Fig. 5, is used to clamp all three extensions to the enfolded rectangular plate 75. This screw, threaded into the plate, is passed through a round hold 1a in the number 1 face of the ribbon A extensions; through a space between face number 5 of the ribbon A extensions and face No. 6 of B extensions; and finally through an elongated hole 90 in face No. 9 of the ribbon C extensions.

The blank for the two ribbon instrument, Fig. 8 is substantially of the same form as shown in Fig. 4 omitting ribbonC, the end extension faces 9 and 10, and the arms, 61), e, and 60, by cutting them off along thedotted line where arms 6?) oiniibbon B. Referring to Fig. 5 the removalof extension faces 9 and 10, requires only an increase in the width and thickness of the plate an amount equal to the thickness of the original blank, in case the parts retained are folded to the dimensions of the three ribbon instrument.

For small instruments needed to draw short radius curves the three ribbon type of Figs. 1 to 6 is preferred. The small instrument must necessarily be made of thin material and any inaccuracies in the relation of one pair of ribbons like AB due to variations in thickness of material or to abnormal strains will, to a large extent, be counteracted by'similar inaccuracies in the other pair B-C taking effect in the opposite direction; For large instruments made of thicker material and in which ordinary abnormal strains will have less effect, the two ribbon type of Fig. 8 may be used. In both types of instrument the outside ribbon A provides the ruling edge, the upper edge of this ribbon being smooth and'free to conform to a uniform smooth curvature. In the two ribbon type, to provide for sufi'icient over-lapping of the V pairs of arms, constituting a protection against distortion under abnormal strains, the angle at the apex of the Vs may be made greater than is necessary in the three ribbon type. A

greater number of arms may also be used by setting them closer together at their points of attachment to the ribbons. I

While the primary purpose of my present invention is to provide a longitudinal flexible body in which two or more relatively movable longitudinal ribbons together with the arms controlling the flexing of the body through that movement are all madeintegral from one piece of material, yet I do not limit m self to that construction only. I may use in conjunction with that construction an auxiliary ribbon of hard uniform highly resilient quality for the sole purpose of increasing the stiffness of the flexible body as a whole. Such a construction is indicated in Fig. 9, the auxiliary ribbon F being placed between the ribbons A and B but not in anyway attached. For this construction the spread relation of the V pairs of arms which control the curvature would still be figured for the center to center distance of ribbons A and B.

The specific purpose and advantage in the use of clamp screws at both ends of the instrument may now be noted. In an instrument with three flexible ribbons and two sets of V pairs of arms whose straight line spreads diminish in opposite directions, like in Fig. 1, the act of springing the instrument from the straight line position to that of a curve will be accompanied by a substantially uniform distribution of the strains developed changing the spreads and will result in a curve of practically the are of a circle. The final accurate adjustment may then be obtained by means of a diagram of curves, bringing the instrument into alignment with the curve of any desired radius and then clamping both ends with the screws.

In an instrument with only two flexible ribbons and one set of V pairs of arms, like Fig. 8, the act of springing the instrument from the straight line position, accompanied bya uniform distribution of the strain developed will result in a curve slightly spiral in character. This condition is then eliminated by bringing both ends of the instrument into alignment with the diagram of the curve desired and then clamping with the screws. The distribution of the strains in the spread of the V pairs of arms from one end to the other will insure the uniformity of the curve sufficiently close for all practical purposes.

I do not limit myself to the adjustment of the instrument providing only a convex ruling edge as shown in F ig. 3. In that figure the adjustment is accomplished by an increase in the spread of the Vs. inn adjustment in the opposite direction may be made through a decrease in the spread of the Vs, providing a concave ruling edge.

It will be obvious that a construction could be used having more than three longitudinal ribbons and more than two sets of V pairs of controlling arms, as shown in Figs. 1 to 6, utilizing the fundamental principle of my in vention. Other modifications in the details of construction may be followed without departure from the essential feaures of the invention as defined in the claims.

I claim as my invention:

1. An adjustable curve ruler comprising a plurality of resilient ribbons, each ribbon having a series of arms integral therewith, extended from the ribbon at fixed angles therewith in planes parallel with the plane of the ruler, integral flexible connections between the ends of the arms of one series and the ends of the arms of another series, permitting a slidable relation between said ribbons and governing the curvature thereof, said ribbons and said arms being all formed from a single blank of resilient material; and means for holding said ribbons when slidably adjusted to any position providing the desired curvature.

2. An adjustable curve ruler having av flexible body and two inflexible end extensions providing tangents to the curve of the flexible body, all punched and formed from a single sheet of resilient material, said flexible body comprising a plurality of longitudinally extending ribbons and a series of arms forming Vs connecting the ribbons, whereby the curvature of the ribbons is governed by the opening or closing of the angle of the Vs;

and means located in the end extensions for clamping and holding the ruler in adjusted shape when the flexible body has been flexed to any desired curvature.

3. An adjustable curve ruler having a flexible body punched and formedfrom a single sheet of resilient material; said body, when formed, comprising a plurality of longitudinally disposed ribbons, one of the ribbons providing the ruling edge, and a series of arms attached to the ribbons and extending on the side opposite the ruling edge and connecting the ribbons in a manner whereby the curvature of the ribbons is governed by a longitudinal movement of the ribbons relative to each other; the said ribbons being arranged relative to each other in a manner whereby the radius of curvature of one ribbon differs from the radius of the associated ribbon an amount equal to the center to center distance between those ribbons.

An adjustable curve ruler having a flexible body comprising three' longitudinally disposed ribbons located in concentric relation to each other, one of the ribbons providing the ruling edge. and two series of arms forming Vs, extending on the side opposite the ruling edge, constituting connections be tween the three ribbons, permitting a relative longitudinal movement of the ribbons and determining the curvature thereof; and means for clamping and holding the ribbons against further relative longitudinal move; ment, thereby holding the flexible body to the curvature secured by that movement.

5. An adjustable curve ruler having a flexible body comprising three longitudinally disposed ribbons located parallel to each other, one of said ribbons constituting the outside or ruling edge, and two series of arms forming Vs extending on the side Opposite the ruling edge, one series of arms connecting through the Vs the outside ribbon with the middle ribbon and the other series connecting the inside ribbon with the middle ribbon, the arms of both series that are attached to the middle ribbon being inclined all in the same direction relative that ribbon, said series of connections through the Vs permitting a relative longitudinal movement of the ribbons and governing the curvatures thereof; and means for clamping and holding the ribbons against further relative longitudinal movement, thereby holding the flexible body to the curvature secured by that movement.

6. An adjustable curve ruler including a flexible ruling edge member and means for controlling the flexing thereof, all formed in one piece from a single blank of material substantially as described.

7. An adjustable curve ruler comprising a flexible ruling edge member and means for controlling the flexing thereof, all integrally punched and formed from a single blank of material, and separate means for locking said flexible member in selected position.

8. An adjustable curve ruler including a pair of flexible, substantially parallel members relatively movable longitudinally of each other, and integrally connected means formed integral with said members for controlling the flexing of said members.

9. An adjustable curve ruler including a pair of elongated flexible members disposed in parallel relation and longitudinally movable relative to each other, and means comprising a plurality of substantially V-shaped Webs of material formed integral with both of said members for controlling the flexing thereof.

10. An adjustable curve ruler comprising a pair of resilient ribbons, each ribbon having a series of arms integral therewith, extended from the ribbon at substantially fixed angles therewith in planes parallel with the plane of the ruler, flexible integral connections between the ends of the arms of one series and the ends of the arms of the other series, said ribbons being bendable into curved position and said connected arms serving to control the curvature of the ribbons, and means for locking said ribbons in selected position of adjustment.

11. An adjustable curve ruler having a flexible body adapted to be bent to a selected curve, and two substantially inflexible end extensions constituting substantially tangent extensions of the curve of the flexible body, all formed from a single sheet of resilient material, said flexible body comprising a pair of ribbons arranged in mutually overlapping relation and slidable relative to each other when bent to a curve, and a series of V- shaped members connecting the ribbons, said V-shaped members having their ends connected respectively to said ribbons whereby relative movement of the latter effects a change in the angle of the V-shaped members and whereby curvature of the ruler .is controlled, and means located in said end extensions for locking the ruler in adjusted position.

12. An adjustable curve ruler having a flexible body comprising three ribbons disposed in concentric parallel relation and relatively adjustable longitudinally, a series of resilient connections between one pair of said ribbons normally tending to maintain the same in predetermined adjusted position, a second series of resilient connections between one of said pair of ribbons and the third ribbon and also tending to maintain said ribbons in predetermined adjusted position, and means for locking said ribbons in selected position of adjustment.

13. An adjustable curve ruler having a flexible body comprising three ribbons disposed in concentric parallel relation and relatively adjustable longitudinally, and two series of V-shapedmembers, one series of said members enveloping the other, the envelope series constituting connections between the outer and intermediate ribbons, the inner series constituting connections between the intermediate and inside ribbons, said V- shaped members being flexible so as to per-- mit said longitudinal adjustment of the rib bons, and means for locking the ribbons in adjusted position.

WILLIAM S. WESTON. 

